Longitudinal asthma and allergy study showed that childhood symptoms frequently persisted into adulthood.

Aims: The prevalence of allergic diseases is high and increasing in many countries. The aim of this study was to describe the prevalence of allergic diseases and changes in clinical expression in a birth cohort followed for three decades.

Methods: We followed Icelandic citizens born in 1987 for allergic diseases when they were 2, 4, 8, 15, 21 and 29 years of age. These were diagnosed using standardised questionnaires, physical examinations and skin-prick tests.

Results: Just under half (46%) of the 112 who took part at 29 years of age had one or more allergic diseases, usually mild. Eczema was confirmed in 14% and was highest at the age of 2 years (31%). The prevalence of asthma was 23% and was highest at the age of 4 years (28%). Allergic rhinitis affected 30% at 29 years of age but was not found before the age of 2 years. In addition, 34% had a positive skin-prick test at 29 years of age.

Conclusion: The results show that 46% of Icelandic adults diagnosed with allergic diseases during childhood still had symptoms at the age of 29, usually mild, developing from eczema in infancy to asthma and allergic rhinitis in adulthood.